Steam-boiler water-level indicator



(No Model.)

J. MoDONALD. STEAM BOILER WATER LEVEL INDICATOR. v

No. 419,967. Patented'Jan.21, 1890.

ammo; My, Mum

UNITED STATES PATENT OFFICE.

JOHN MCDONALD, OF PITTSBURG, PENNSYLVANIA.

STEAM-BOILER WATER-LEVEL INDICATOR.

SPECIFICATION forming part of Letters Patent No. 419,967, dated January21, 1890.

Application filed July 28, 1888. seanmzanssa (no model) To all whom itmay concern.-

Be it known that I, JOHN MCDONALD, of the city of Pittsburg, in thecounty of Allegheny and State of Pennsylvania, have invented a new anduseful Improvement in Steam-Boiler Indicators; and I do hereby declarethe following to be a full, clear, and exstructed with alarms-either awhistle, the

valve of which is operated by a float in the boiler, or an electricala1arm-bell, the circuit of which is controlled by a similar float. Suchdevices are, however, objectionable, because they tend to cause theengineer to rely too much on the working of the apparatus and to becomecareless in his attention to the boiler, and if forany reason theapparatus should get out of ordgr the safety of the boiler might beendangerec.

To obviate this objection I have devised the present invention, whichconsists in an apparatus which is so constructed as to mark and keep anaccurate record of the quantity of water in the boiler at all times, thepurpose being to give to the employer means of observing what thewater-level has been at any time, and thus enabling him to detect anylack of attention on the part of the engineer, such apparatus includingan automatic signal which shall indicate any dangerous elevation or fallof the water.

Referring now to the drawing, 2 represents the steam-boiler.

3 is a float in the boiler, having a projecting arm 4, which is fixed toa short rotary shaft 5. This shaft passes through a stuffing-box 6 inthe boiler-head, and has fixed to it on the outside of the boiler apointer or indicating-finger 7. When thus constructed, it is evidentthat any rise or fall of the float, owing to variation in thewaterdevel, will aifect a radial motion of the pointer 7, either to theright or to the left, accordingly as the water rises or falls.

8 is a dial plate or card, which is set in a suitable case 9, and ismoved therein, preferably in a rotary direction, as indicated by thearrow, by means of suitable clock-work, so that as it rotates its faceshall be in contact with a pencil or stylus 10 at the end of the pointer7. As the card rotates, the pencil will produce a mark thereon, which,if the waterlevel be constant, will be exactly circular; but if thefloat is moved 'by variation of the water-level the pencil will be movedto the right or left, and the mark on the card will be correspondinglyirregular. It follows, therefore, that if the instant of time when anygiven point on the card passes the stylus be known the position of themark at that point will indicate what the water-level is at that time,it being known, of course, what point on the dial will be marked at themean waterlevel. To this end I divide the card radially into divisionsrepresentingdivisions of time. In the drawing I show it divided intoseven principal parts, representing the days of the week, and havingsubdivisions indicating the hours of each day, The lines indicatingthese divisions should correspond to the motion of the pointer, and inthe arrangement which I show in the drawing should be made on arcs of acircle described on a center coincident with the axis of the pointer andwhose radius is the distance from the axis of the pointer 7 to thestylus. The card may of course be divided by a greater or less number ofmarks to indicate, for example, the boiler variations for two weeks, fora day, or for any other pe .riod of time, and the clock-work whichdrives the card should be timed to impart to it one complete revolutionin the period during which the card is designed to record. The card isinclosed in a case, preferably with a glass cover, and the case may belocked, so as to prevent tampering with the instrument. It affords atall times an accurate record of the condition of the water-level, eitherat the present moment or at a previous time, which is apparent onglancing at the card, and if the engineer carelessly allows the water'tofall too low he does so at the risk of detection. of his carelessness byhis official superiors. Thus the card shown in the drawing indicatesthat from twelve oclock on Mondaymorning until four oclock on Fridaymorning the water-level was substantially the same, with only slightfluctuations above or below the normal level, and that at the time lastnamed the water-level suddenly fell, and that it remained at a low leveluntil six oclock, when it rose again to the normal level and continuedso until Friday noon. lVhen the markon the card has traversed the entirecircle, the card may be removed and either preserved as a record orthrown away, and a fresh card is substituted for it. I use anelectro-magnetic bell 12, and in the circuit of its conductors place abattery 13. The end of one conductor is electrically connected with thepointer 7, and the other conductor is connected with a metallic contactring or plate 1%, which is fixed to the case near the center of motionof the dial, and is also connected with a second metallic contact ringor plate 15, which is fixed to the case at or near the rim of the dial.The pointer is made of metal, and if the water-level should change ineither direction sufficiently to reach the danger limit the consequentunusual motion of the pointer to the right or left would bring it intocontact with either the plate 14: or 15, in either case completing thecircuit through the battery and bell-magnet and causing the bell toring.

The apparatus which I have described and shown is one of great utilityand merit, and its numerous advantages will be appreciated by thoseskilled in the art.

The apparatus may be varied greatly in form, size, and details ofconstruction by me chanical changes such as will suggest themselves tothe skilled mechanic, and I do not in the broad claims of this patentintend to limit my invention to the precise arrangement and constructionwhich I have shown and described; but

What I claim is- A recording water-indicator for stcan1-boilers,comprising a pointer, a rotatable card having a metallic center plate 14and a metallic rim-plate 15, with which the pointer may come intocontact, an electric circuit including said plates and the pointer, andan alarm, substantially as and for the purpose described.

In testimony whereof I have hereunto set my hand this 25th day of July,A. D. 1888.

. JOHN MCDONALD.

Witnesses:

W. B. Conwm, THOMAS W. BAKEWELL.

